With traditional telephony, the local phone company delivers
telephony services over a wire, or a “trunk,” that connects the
corporate PBX to the PSTN. This physical trunk, made up of
multiple channels, carries phone calls from the corporation out
to the PSTN, allowing the company to have phone service.
trunking allows companies to replace these physical circuits with “virtual trunks” that are deployed over any data connection. This connection can be a dedicated data circuit or a shared connection with a data service, or companies can even use the Internet for connectivity if they so choose. Because the service is emulated over a data connection, organizations can pool a group of trunks together and allocate bandwidth as dictated by business policy.
SIP trunking delivers much more value to an organization than traditional PSTN trunks do. First, there’s no actual limit to the number of user voice sessions that can be carried over a SIP trunk—the limit is governed by bandwidth, not number of channels. A traditional PSTN trunk limits the number of calls to the number of channels available (typically 24 per trunk).
SIP trunking scales by bandwidth, so need more calls to go through? Increase the bandwidth of the connection instead of deploying another physical one. Also, in addition to voice services, many Unified Communication
services can be more efficiently deployed over SIP. SIP trunking makes it simpler to layer on additional Unified Communication applications such as chat services, presence, conferencing, application sharing and video.
SIP trunking allows organizations to extend VoIP past the corporate network, where most deployments end today. It removes the need for organizations to purchase costly gateways,bridges or other equipment to connect the corporate Unified Communication environment to the PSTN. Instead, these are connected by the network of the telecommunications provider, so the enterprise does not have to incur the cost.
Overall, SIP trunking is a simple, cost-effective method of increasing the ROI of a Unified Communication rollout.
Although SIP trunking is a network technology, its benefits can be realized not only by the IT and network groups, but also at an end-user level. Organizations that choose to embrace SIP trunking will realize the following benefits:
Lower costs due to reduction in the overall number of trunks. Because many new IP PBXs are designed to operate from a centralized architecture, each location in the network can receive call control over the WAN, allowing SIP trunks to be centralized. Centralization can be at a company level, a regional level or any other way the company chooses to architect the network. This is similar to the way other IP applications are deployed in companies today, and it
can save organizations thousands of dollars per month. The majority of cost savings come from decreasing the number of trunks required, but there are also operational savings to be gained from a centralized architecture.
Better utilization of trunks. Since trunk lines are brought
in over an IP connection, organizations can deploy
fewer, bigger trunks to handle the calling needs of a greater part
of the organization. Additionally, because global organizations
typically have reduced calling needs when the local region
reaches nightfall, the call capacity can be pooled together and
used more efficiently.
Lower intra-enterprise calling costs. All on-net calls (that
is, calls within a corporation) are kept on the corporate data
network, meaning the cost of these calls can be eliminated
altogether or at least greatly reduced, depending on architecture.
Cost savings will vary by organization type. A large, distributed
multinational company will save orders of magnitude more than a
large company located in a single building.
Better network reliability than traditional PSTN. The
thought that VoIP is any less reliable than traditional voice is one
of the biggest myths holding back greater adoption of VoIP. IP is
a resilient protocol and reliability can be built into the design. For
example, instead of having separate voice and data networks, a
company could choose to deploy two data networks that could
act as a backup for one another. This would cost no more than
the traditional model but could protect against any network
outage. It would also provide better disaster recovery capabilities
than running separate networks.
Simplified network management Because all traffic runs
on a common data network, it is easier to manage and plan
for future capacity. Converged networks create converged
Extension of IP communications all the way to the
carrier network. This has two benefits. First, there is no
IP-to-PSTN conversion needed, which improves call quality.
Additionally, as more call capacity is needed, it can be added
almost on demand, and then reduced later as the situation
warrants. This is a significantly faster way of adding capacity
compared with having to order new Primary Rate Interface
(PRI) links and then waiting for them to be installed. For
example, an organization could quickly add capacity if it were to
open a number of new branch offices. Conversely, a university
could quickly lower capacity during the summer season when
call volume is lower.
SIP trunking is a simple, cost-effective method of accelerating the deployment of Unified Communication and gaining new efficiencies. SIP trunking should be
thought of as a core building block of Unified Communication - as important as the underlying IP network. A Unified Communication deployment built on SIP trunking allows companies
to achieve the following benefits:
Reduced overall communications costs
More efficient use of network assets
Accelerated deployment of current and future Uinified Communication applications through the simplification of network design
Higher reliability and better disaster recovery capabilities than traditional TDM-based systems